Hung Sau Wai, Marrache Sean, Cummins Shannon, Bhutia Yangzom D, Mody Hardik, Hooks Shelley B, Dhar Shanta, Govindarajan Rajgopal
Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, USA.
Department of Chemistry, University of Georgia, Athens, GA, USA.
Cancer Lett. 2015 Apr 10;359(2):233-40. doi: 10.1016/j.canlet.2015.01.017. Epub 2015 Jan 16.
Nucleoside analogs are used as chemotherapeutic options for the treatment of platinum-resistant ovarian cancers. Human concentrative nucleoside transporter 1 (hCNT1) is implicated in sensitizing solid tumors to nucleoside analogs although its role in determining drug efficacy in ovarian cancers remains unclear. Here we examined the functional expression of hCNT1 and compared its contributions toward gemcitabine efficacy in histological subtypes of ovarian cancer. Radioactivity analysis identified hCNT1-mediated (3)H-gemcitabine transport in ovarian cancer cells to be significantly reduced compared with that of normal ovarian surface epithelial cells. Biochemical and immunocytochemical analysis identified that unlike normal ovarian cells which expressed high levels of hCNT1 at the apical cell surface, the transporter was either diminished in expression and/or mislocalized in cell lines of various subtypes of ovarian cancer. Retroviral expression of hCNT1 selectively rescued gemcitabine transport in cell lines representing serous, teratocarcinoma, and endometrioid subtypes, but not clear cell carcinoma (CCC). In addition, exogenous hCNT1 predominantly accumulated in intracytoplasmic vesicles in CCC suggesting defective cellular trafficking of hCNT1 as a contributing factor to transport deficiency. Despite diminution of hCNT1 transport in the majority of ovarian cancers and apparent trafficking defects with CCC, the chemotherapeutic efficacy of gemcitabine was broadly enhanced in all subtypes when delivered via engineered nanoparticles (NPs). Additionally, by bypassing the transport requirement, the delivery of a gemcitabine-cisplatin combination in NP formulation increased their synergistic interactions. These findings uncover hCNT1 as a putative determinant for nucleoside analog chemoresistance in ovarian cancer and may help rationalize drug selection and delivery strategies for various histological subtypes of ovarian cancer.
核苷类似物被用作治疗铂耐药卵巢癌的化疗选择。人浓缩核苷转运体1（hCNT1）与实体瘤对核苷类似物的致敏作用有关，尽管其在确定卵巢癌药物疗效中的作用仍不清楚。在此，我们检测了hCNT1的功能表达，并比较了其在卵巢癌组织学亚型中对吉西他滨疗效的贡献。放射性分析表明，与正常卵巢表面上皮细胞相比，卵巢癌细胞中hCNT1介导的（3）H-吉西他滨转运显著降低。生化和免疫细胞化学分析表明，与在顶端细胞表面表达高水平hCNT1的正常卵巢细胞不同，该转运体在各种卵巢癌亚型的细胞系中表达减少和/或定位错误。hCNT1的逆转录病毒表达选择性地挽救了代表浆液性、畸胎癌和子宫内膜样亚型的细胞系中的吉西他滨转运，但对透明细胞癌（CCC）无效。此外，外源性hCNT1主要积聚在CCC的胞浆内小泡中，提示hCNT1的细胞转运缺陷是转运不足的一个促成因素。尽管大多数卵巢癌中hCNT1转运减少，且CCC存在明显的转运缺陷，但通过工程化纳米颗粒（NP）递送时，吉西他滨在所有亚型中的化疗疗效均得到广泛提高。此外，通过绕过转运需求，NP制剂中吉西他滨-顺铂组合的递送增加了它们的协同相互作用。这些发现揭示了hCNT1是卵巢癌中核苷类似物化疗耐药的一个推定决定因素，可能有助于合理化各种卵巢癌组织学亚型的药物选择和递送策略。
